#include<stdio.h> 

double result_real, result_imag;
void complex_prod( double x1, double y1, double x2, double y2 );

int main(void) 
{ 
    double imag1, imag2, real1, real2;    

    scanf("%lf %lf", &real1, &imag1);             
    scanf("%lf %lf", &real2, &imag2);             
    complex_prod(real1, imag1, real2, imag2);     
    printf("product of complex is (%f)+(%f)i\n", result_real, result_imag);
    
    return 0;
}

void complex_prod( double x1, double y1, double x2, double y2 ){
    result_real=x1*x2-y1*y2;
    result_imag=x1*y2+x2*y1;
}
